Angiogenesis, the formation of new blood vessels and consequently increased blood circulation, and angiogenic factors, chemical compositions which initiate and mediate the formation of new blood vessels and circulation, have been a favorite area of research and investigation for many years. Much of this interest stems from the recognition that normal tissues in humans and animals can contain trace amounts of angiogenic compositions but do not show any angiogenic activity other than in the normal process of growth and development of tissues and organs. Angiogenesis and angiogenic factors have been observed, isolated, and purified mainly from pathological tissues of various kinds. For example, the significance of the interaction between the host vasculature and the survival and growth of solid malignant tumors has been recognized for well over a century [Virchow, R., Die Krankhaften Geshwulste, Hirshwald, Berlin, 1863; Thiersch, C., Der Epithelialkrebs, Nanentlich Der Haut Mit Atlas, Lipzig, 1865]. However, the first clear cut demonstration of the existence of a humoral, angiogenic factor was first demonstrated by Greenblatt and Schubik in their transfilter diffusion studies [J. Natl. Cancer lnst. 41:111-124(1968)]. Subsequent investigations of this tumor angiogenic factor has produced major differences and discrepancies in describing the composition and characteristics of the active factor [Folkman et al., J. Exp. Med. 133:275(1971); Weiss et al., Br. J. Cancer 40:493(1979); McAuslan et al., Exp. Cell Res. 119:181-190(1979); Fenselau et al.. J. Biol. Chem. 256:9605-9611(1981)]. These investigations of the tumor angiogenic factor has led to concurrent research efforts by others for additional or similar chemical compositions. These include: the isolation of an angiogenic factor from synovial fluid resembling that from tumors having a molecular weight of approximately 200-300 daltons [Brown et al., Lancet I:682-685(1980)]. A proteinaceous angiogenic factor from human myocardial infarcts ranging from 300-1.times.10.sup.5 daltons [Kumar et al., Lancet II :364-367(1983)]. Angiogenic factors in the vitreous fluid of humans with diabetic retinopathy and in the retinas of animals comprising proteins and polypeptides up to 70,000 daltons in molecular weight [Hill et al., Experientia 39:583-585(1983); D. Amore et al., Proc. Natl. Acad. Sci. USA 78:3068-3072(1981); Kissun et al., Br. J. Ophth. 66:165-169(1982)]. The isolation of an angiogenic protein from wound fluid having a molecular weight between 2,000 and 14,000 daltons [Banda et al., Proc. Natl. Acad. Sci. USA 79:7773-7777(1982)]. Protein complexes ranging from 100,000-200 daltons irom human amino-chorion and placenta which show angiogenic activity [Burgos, H., Eur. J. Clin. Invest. 13:289-296(1983)]. Poorly defined aqueous extracts which stimulate neovascularization from 3T3 adipocytes and human follicular fluid [Castellot et al., Proc. Natl Acad. Sci. USA 79:5597-5601(1982); Frederick et al., Science 224:389-390(1984)].
A method to isolate human tumor angiogenic factor (TAF) and factor from: non-tumors is described in a series of patents by Tolbert et al. [4,209,587 issued June 24, 1980; 4,217,412 issued Aug. 12, 1980; 4,225,670 issued Sept. 30, 1980; 4,229,531 and 4,229,532 issued Oct. 21, 1980; 4,268,629 issued May 19, 1981 and 4,273,871 issued June 16, 1981]. These relate only to a method of preparing crude factor from cell culture supernatants. 4,217,412 issued Aug. 12, 1980; 4,225670 issued Sept. 30, 1980; 4,229,531 and 4,229,532 issued Oct. 21, 1980; 4,268,629 issued May 19, 1981 and 4,273,871 issued June 16, 1981). These relate only to a method for preparing crude factor from cell culture supernatants and are completely unrelated to the source and method of the angiogenesis factor claimed below.
The overall effect and conclusion drawn from these various research efforts may be summarized as follows: first, the angiogenic factor, regardless of source, has almost always been shown to be a protein, a protein complex, or a polypeptide in nature. Second, the true chemical structures of any of these compositions able to initiate or mediate angiogenesis has not yet been accurately described in detail; to the contrary, the variation and discrepancies of data from different groups of investigators regarding the molecular weight, between the multiplicity of compounds interacting to produce an angiogenic effect, and by the ability (or inability to) obtain a homogeneous purified preparation has been enormous. Lastly, the overwhelming majority of angiogenic factors previously reported have been required to be used as implanted pellets or preparations which slowly release the active factor over time in order to effect angiogenesis; this is believed due to the short life span, the high diffusibility and relatively low biological activity of the factors.
A totally different approach to angiogenesis is the surgical application of intact omentum to normal and traumatized tissues in the body by Harry S. Goldsmith and his coworkers [Goldsmith et al., Arch. Surg. 106:695-698(1973); Goldsmith et al., Am. J. Surg. 130:317-320(1975); Goldsmith et al., Am. J. Surg. 29:263-265(1975); Goldsmith et al., Stroke 9:224-229(1978); Goldsmith, H. S., Rev. Surg. 24:379-380(1967); Goldsmith, H. S., Surgery 88:732-736(1980); Goldsmith et al., "Application Of Intact Omentum To The Normal And Traumatized Spinal Cord", in Spinal Cord Reconstruction, Raven Press, New York, 1983, pages 235-244]. These efforts demonstrated that the surgical attachment of intact omentum directly on the surfaces of the brain or spinal cord resulted in vascular anastomoses between the omentum and the other tissues sufficient to prevent infarction even in the presence of middle cerebral artery ligation. Gross examination and microscopic histological examination showed substantial development of vascular connections between the omentum in each of the tested tissues in the sacrificed animals. There is no description and no indication, however, in any of these reports regarding the particular factors, chemical or physiological, which cause the demonstrated neovascularization. Moreover, it is far from clear from any of the reported findings, that the omental factors have any similarity to those proteinaceous factors derived from tumors and the like as described herein previously.